The invention relates to a machine tool provided with a fluid supplying unit which supplies fluid to a workpiece chucking unit via a spindle.
It is known that a front face of a workpiece is machined by a headstock and a tool post and then a back face of the workpiece chucked by a collet of a sub spindle is machined by a backworking unit. In such a lathe, oil or air is supplied to the sub spindle to block cut chips from entering the sub spindle through a slit of the collet. Japanese patent application publication No. 2009-172725, especially the paragraph 0035 discloses a backworking unit provided with a blow air supplying mechanism and a cutting oil supplying mechanism.